<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>
  <div id="app">
    =={{msg}}==={{val}}
    <hr />
    <input type="text" name="" id="" @input="handle" :value="val">
  </div>
  <script src="https://cdn.bootcdn.net/ajax/libs/vue/2.7.14/vue.min.js"></script>
  <script>
    var vm = new Vue({
      el: "#app",
      data: {
        msg: 'hello  vue',
        val: ''
      },
      methods: {
        handle (e) {
          console.log(e.target.value);
          this.val = e.target.value
        }
      }
    })

    // console.log(vm, 2222);
  </script>
</body>

</html>